NAPLES, Florida, - A strenthened Hurricane Wilma barreled toward the US state of Florida early Monday as officials urged residents to leave the coastal area or move to shelters.

Wilma was upgraded late Sunday to a category three storm after it displayed sustained winds of 185 km (115 mi) an hour, which qualified it for category three status. No further significant changes are expected in the strength of Wilma until it makes landfall in Florida early Monday.

At 0300 GMT, the eye of the storm was located 275 kilometers (170 miles) southwest of Naples and barreling toward the US coast at 30 kilometers (18 miles) an hour.

A storm surge up to 2.5 meters (5-8 feet) above normal was forecast for the Florida Keys and Florida Bay.

This is a very dangerous hurricane

hurricane center director Max Mayfield told CNN television, urging those who have not yet evacuated the coastal area to do so and find a reliable shelter.

In the Florida Keys island chain at the state's southern tip, residents who refused to leave were told to find a safe place to weather the storm and were warned that they were staying at their own risk.

Residents of the city of Naples, on the southwest coast, were also told to stop evacuating and take shelter as the storm approached with winds of 175 kilometers (110 miles) per hour.

Florida Keys residents had been ordered out on Saturday, but many of the 80,000 residents ignored the call. Earlier, Governor Jeb Bush had made a last-minute appeal for residents still in Wilma's path.

I cannot emphasize enough to the folks that live in the Florida Keys a hurricane is coming, and a hurricane is a hurricane and it has deadly force winds

Bush also said 2,400 National Guard troops were mobilized, while trucks packed with emergency aid and more than 30 rescue helicopters were ready. He said authorities expected power outages and flooding.

The Kennedy Space Center in Cape Canaveral, where the space shuttle is launched, closed and told employees to stay home Monday. NASA also said it closed the payload bay doors of the shuttles Discovery, Endeavour and Atlantis and placed the New Horizons spacecraft, which will blast off in a mission to Pluto next year, in a protective canister.

Wilma killed at least eight people when it struck Mexico. Four bodies were found on the island of Cozumel, where there has been three days of torrential rain and roofs were ripped off many buildings.

The governor of Quintana Roo state said two people died in Playa del Carmen, one in Cancun and a fourth in Yucatan state crushed by a tree. Two fishermen were also missing at sea.

More than 71,000 people, many of them foreign tourists, remained in emergency shelters for a third day, unable to leave because of the floods and damage.

Looters took advantage of the chaos. Scores were out at dawn in Cancun and other tourist spots, raiding appliance stores for televisions, washing machines and other goods, and stealing liquor and clothes.

More than 600 federal police and troops were ordered into the stricken resorts to stop the looting. President Vicente Fox visited Cancun as well as other storm-hit areas.

Wilma also inflicted heavy damage on a naval base on Cozumel, officials said. Cozumel, famous among snorkelers and scuba divers, was devastated following the storm, with streets flooded, according to the interior ministry.

Wilma pounded western Cuba with heavy rain, floods and high winds. Four people died in Cuba after a bus ferrying tourists away from areas threatened by Wilma slipped off a wet road Friday, authorities said on Sunday.

About 640,000 people had been evacuated from Cuban coastal areas. The Caribbean was earlier threatened by Tropical Storm Alpha, which became the 22nd storm of the Atlantic season, breaking the all-time record for the most active season in the Atlantic basin.

Alpha, however, was later downgraded to a tropical depression.